This invention relates generally to imaging methods and apparatus, and more particularly, to methods and apparatus that provide for improvements in x-ray detector fabrication.
X-ray detectors typically include a photodiode portion and a scintillator portion. An x-ray enters the detector and impinges the scintillator material, wherein photons of visible light are created. The visible light then leaves the scintillator material and impinges a photodiode. The photodiodes are polled, returning attenuation measurements. This data is then used to create images. In assembling a detector (i.e., a photo-diode and scintillator array), there are two important components in controlling the cross talk.
Alignment of the scintillator elements to the photodiode active areas is important. Any misalignment of the scintillator portion to the photodiode portion increases the optical cross talk. Cross talk is where one diode receives energy that in a perfect world would have been received in another diode. One way to align the elements is by using fixtures. However, fixture based approaches may not provide adequate alignment capability.
Additionally, it is desirable to assemble detectors using so-called “pick and place” technology. “Pick and place” technology means using robotic arms that move fast and accurately but are also expensive to implement. In order to utilize “pick and place” technology in a cost effective manner the alignment must be “frozen” relatively quickly. By “frozen”, it is meant that the two parts are held together strongly enough that the robotic arm can release the picked part and the assembly can undergo typical assembly handling, even though a stronger bond is eventually obtained.
Additionally, the size of the space between the scintillator elements and the photo diode is important, as is the consistency of that spacing. To maximize the light transportation between the scintillator material and the photodiode, an optical coupler material may be used (the optical coupler material reduces any light bouncing back from the surface of the photodiode). Therefore, in addition to providing a non-fixture approach, it is desirable to provide an approach wherein the space between the scintillator material and the photodiode is consistent.